Stabilization of tetrahydrofuran



Patented Oct. 10, 1950 UNITED STATES PATENT OFFICE STABILIZATION 0F TETRAHYDROFURAN Wilbie S. Hinegardner, Niagara Falls, N. Y., as-

signor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware No Drawing. Application December 19, 1946,

Serial No. 717,315

2 Claims.

This invention relates to the stabilization of heterocyclic organic compounds and in particular it relates to the stabilization of tetrahydrofuran.

Tetrahydrofuran is a colorless liquid which is a potentially important and valuable intermediate for the preparation of a wide variety of organic compounds. An obstacle to its extensive use is the fact that it forms peroxides during storage. Although freshly distilled tetrahydrofuran sometimes contains small concentrations of peroxide, in the order of a few hundredths of one per cent, which are relatively harmless, upon standing for a comparatively short period, the peroxide concentration rapidly increases to the point where the material becomes unsafe to handle. Peroxide formation in tetrahydrofuran not only introduces an undesirable impurity but also results in a hazardous condition since'the peroxide formed may decompose with explosive violence when relatively high concentrations are present part cularly when the material is distilled or heated. No method has heretofore been available for stabilizing tetrahydrofuran.

It is an object of this invention to provide a novel method for the stabilization of tetrahydrofuran. Another object is to inhibit peroxide formation in tetrahydrofuran. A further object is to provide a new stabilizer for tetrahydrofuran. An additional object is to provide a relatively stable tetrahydrofuran composition. These and other objects will be apparent from the following description of my invention.

The above objects are attained in accordance with my invention by incorporating into tetrahydrofuran hydroquinone.

I have discovered that when small amounts of hydroquinone are incorporated into tetrahydrofuran peroxide formation is substantially inh bited and a relatively stable composition results. Tetrahydrofuran stabilized in accordance with my invention may be stored over relatively long periods without the development of hazardous concentrations of peroxide.

Various concentrations of hydroquinone may be utilized in the practice of my invention although I prefer to utilize concentrations within the range 0.05 to 1.0% by weight. Concentrations above 1.0% may be used successfully but in general amounts greater than 1.0% are unncessary for satisfactory results. Less than 0.05% of hydroquinone may be utilized but for consistently satisfactory results concentrations of at least Example A glass-stoppered clear glass bottle was half filled with freshly distilled anhydrous tetrahydrofuran containing 0.1 hydroquinone. The bottle containing the tetrahydrofuran and hydroquinone was stored in diifused light and an analysis of the peroxide content was made from time to time. The analysis for peroxide content was made by pipetting a 10 cc. sample of tetrahydrofuran into an excess of potassium iodide in dilute sulfuric acid solution and allowing the sample to stand in the dark during 10 minutes. The liberated iodine was then determined by titration with a standard sodium thiosulfate solution. A second sample containing 0.05% hyroquinone was prepared and tested in the same manner. The results are shown in tabular form below:

00. 0.1 N Thiosulfate/lO cc. Sample Time in Days Control (No 0.05% 0.1%

Hydro- Hydro- Hydroquinone) quinone quinone 1 One cc. of this solution/l0 cc. sample of tetrahydrofuran is equivalent to approximately 0.05% peroxide when it is assumed that the peroxide contains one mole of tetrahydrofuran.

The foregoing data conclusively demonstrate the inhibiting effect of hydroquinone on peroxide formation in tetrahydrofuran. No appreciable tively long periods or shipped long distances without appreciable deterioration but also the 7 3 hazard inherent in the presence of peroxides in UNITED STATES PATENTS the tetrahydrofuran is held to a minimum. Number Name Date I clam r 2,114,832 Evans Apr. 19,1938 1. The method for stabilizing tetrahydrofuran 2,489,260 Bordner Nov. 29, 1949 which comprises incorporating therein 0.05 to 5 1.0% of hydroquinone. OREIGN PATENTS 2. A stable tetrahydrofuran composition com- Number Country t prising tetrahydrofuran ha ling inco p r 532,158 Great Britain Jan. 17, 1941 therein 0.05 to 1.0% of hydroqulnone. 10 OTHER REFERENCES WILBIE S. HINEGARDNER. Gilman: Organic Chem. An Advanced Treatise, vol. I, 2nd edition, pages 656 and 657. John REFERENCES CITED Wiley and Sons, New York.

The following references are of record in the Daubert: Amer Pharm' ASS-y pages file of this patent:

Chem. Abstracts, volume 39, page 2024. 

1. THE METHOD FOR STABILIZING TETRAHYDROFURAN WHICH COMPRISES INCORPORATING THEREIN 0.05 TO 1.0% OF HYDROQUINONE. 